U.S. Pat. No. 4,105,776, issued Aug. 8, 1978 describes a group of thioalkanoyl derivatives of azetidine-, pyrrolidine-and piperidinecarboxylic acid compounds having the structural formula ##STR3## wherein the symbols can be, inter alia, as follows: R.sub.a can be hydrogen, lower alkyl, phenyl, substituted phenyl, phenyl-lower alkyl, ##STR4## R.sub.b can be hydrogen, R.sub.c can be hydrogen or lower alkyl, R.sub.d can be hydrogen, hydroxy or lower alkyl, R.sub.e can be hydroxy, --NH.sub.2 or lower alkoxy, n' can be 0,1 or 2 and m can be 1, 2 or 3. The compounds, and the salts thereof, are disclosed as being useful as inhibitors of the conversion of the decapeptide angiotensin I to angiotensin II, and are, therefore, useful in reducing or relieving angiotensin related hypertension. Among the salts disclosed are amino acid salts.
U.S. Pat. No. 3,246,025, issued Apr. 12, 1966 .alpha.-and .beta.-mercaptopropionylglycine and esters and amides thereof. The compounds are disclosed as being useful for the treatment of drug intoxication and poisoning and for strengthening liver function.
U.S. Pat. No. 3,897,480 issued July 29, 1975 discloses N-(mercaptoacyl)amino acids having the formula ##STR5## wherein the symbols can be as follows: R.sub.f can be alkyl, aryl or arylalkyl, R.sub.g can be hydrogen, alkyl, aryl or arylalkyl and n" can be 0, 1, 2, 3 or 4 with various provisos that further limit the disclosure. The compounds are disclosed as having an accelerating action for the elimination of a heavy metal such as mercury from the body, an eliminating action with respect to a substance harmful to the body such as a free radical or a peroxide; and an accelerating action of metabolism.